Speaker
Description
Scanning transmission electron microscopy (STEM) in combination with electron energy-loss spectroscopy (EELS) is probably the most versatile spectroscopy technique to study materials at sub-nanometer length scales. For instance, nowadays it is possible to obtain chemical maps of composition, bonding information and dielectric response of materials [1]. EELS measurements and mapping were carried out in TEM/STEMs till 2000, but since then mapping with atomic resolution (d < 2 Å) has become routinely possible with the advent of aberration-corrected STEMs [2].
Improvements in the understanding of the scattering process involved in EELS has also led to measure and quantify ferromagnetic phases in materials, just like with X-ray circular magnetic dichroism (XMCD) in synchrotrons, but with the phase of the electron playing the role of polarization of light [3].
The recent development of a new generation of monochromators [4] and spectrometers [5] has transformed EELS in a much more versatile tool. Phonon mapping with atomic resolution [6], the detection of isotopes in water [7] and amino acids [8] for instance, are now the new ‘tools’ of this Swiss Army Knife of spectroscopy that is EELS.
I will go through some of the technical details of the aforementioned tools and discuss some of the relevant ‘blades and tools’ of the monochromated-EELS toolkit that I think would be must relevant to the Catalan research community.
References:
[1] R.F. Egerton, Electron Energy-Loss Spectroscopy in the Electron Microscope, 3rd edition (Springer, 2011).
[2] D.A. Muller et al., Science 319 (2008) p. 1073.
[3] P. Schattschneider, et al., Nature 441 (2006) p. 486.
[4] O. L. Krivanek, et al., Phil. Trans. R. Soc. A 367 (2009), p. 3683.
[5] T.C. Lovejoy et al., Micros. & Microanal. 24 (2018) p. 446.
[6] F. S. Hage et al., Phys. Rev. Lett. 122 (2019), p. 016103.
[9] J.R. Jokisaari, et al., Adv. Mater. 30 (2018), p. 1802702.
[10] J.A Hachtel, et al., Science 363 (2019), p. 525.
